Inhibitory Effect Of Essential Oils Research Articles

Inhibition of elastase activity by essential oils in vitro

Essential oils are widely used, for example in aromatherapy and aroma massage. In aroma massage, essential oil, diluted with vegetable oil, is rubbed onto the skin. Components of essential oil penetrate into the skin and have an influence on the dermis. Elastase is an enzyme which degenerates dermal elastin. Elastase activity is believed to contribute to cutaneous wrinkling and ageing. To investigate the inhibitory effect of essential oils on elastase activity. Inhibition of elastase activity by various essential oils was assessed using two elastase enzymes: porcine pancreatic elastase (PPE) and human neutrophil elastase (HNE). Elastase activity was inhibited by various essential oils, especially by those oils derived from lemons, juniper and grapefruit. Although the specific inhibitory component was not determined, lemon oil had the greatest inhibitory effect on PPE. Some essential oils also inhibited HNE. These studies demonstrate a possible rationale for the use of essential oil massage as a preventive treatment for cutaneous wrinkling and ageing.

Screening for Inhibitory Activity of Essential Oils on Selected Bacteria, Fungi and Viruses

The purpose of this study was to examine the inhibitory effect of essential oils against a broad spectrum of microorganisms including bacteria, yeast, molds, and two bacteriophage. The inhibitory effects of 45 oils on eight bacteria (four Gram positive and four Gram negative), two fungi, and one yeast were examined using the disk assay method. Phage inhibition was measured by mixing the oils with a phage suspension, incubating the mixture at 4°C for 24 h, then plating on a lawn of indicator bacteria and assaying for plaque production. Of the oils tested, all oils exhibited inhibition over activity relative to controls. However, a number exhibited only weak inhibition against several gram positive bacteria. Gram negative bacteria were generally more resistant than Gram positive bacteria to oil treatment with Pseudomonas aeruginosa being the most resistant bacteria. Only cinnamon bark (Cinnamomum zeylanicum) and tea tree (Melaleuca alternifolia) oils showed an inhibitory effect against all the test organisms and phage. Coriander oil (Coriandrum sativum) highly inhibited Gram positive bacteria and fungi. Lemongrass (Cymbopogon flexuosus) and Roman chamomile (Chamaemelum nobile) oils showed a high degree of inhibition against both phage types, while 8 oils showed no inhibition against either phage. Angelica (Angelica archangelicd) and pine (Pinus sylvestris) oils inhibited the bacteria, but had no effect on any fungi. Oils that exhibited high antimicrobial properties and the broadest range of inhibition included cinnamon bark (Cinnamomum zeylanicum), lemongrass (Cymbopogon flexuosus), savory (Satureja montana), Roman chamomile (Cbamaemelum nobile), rosewood (Aniba rosaeodora), spearmint (Mentha spicata) and tea tree (Melaleuca alternifolia).

Inhibitory Effects of Essential Oil of Psamogeton canescens on Asexsual Reproduction of Toxigenic Fungi (Strains of Aspergillus)

Inhibitory Effects of Essential Oil of Psamogeton canescens on Asexsual Reproduction of Toxigenic Fungi (Strains of Aspergillus)

Inhibitory effect of essential oils on apical growth of Aspergillus fumigatus by vapour contact.

The inhibitory effect of seven essential oils on the apical growth of hyphae of Aspergillus fumigatus was studied using a bio cell tracer by vapour contact in a sealed vessel. Based on the inhibitory pattern, these essential oils were classified into three groups. The first group, composed of citron, lavender and tea tree oils, stopped the apical growth in a loading dose of 63 micrograms ml-1 air, but allowed the regrowth of the hyphae after removal of the vapour, indicating fungistatic action. The second group, consisting of perilla and lemon-grass oils, stopped the apical growth in a loading dose of 6.3 micrograms ml-1 air, and did not allow the regrowth after gaseous contact at 63 micrograms ml-1 air, indicative of fungicidal action. The third group, consisting of cinnamon bark and thyme oils, retarded the growth in a dose of 6.3 micrograms ml-1 air, stopped it in a dose of 63 micrograms ml-1 air, and incompletely suppressed regrowth of the hyphae. Gas chromatographic analysis revealed that vapours of essential oils were absorbed on fungal mycelia and agar medium most abundantly by the first group, followed by the second and third groups, reflecting the volatility of the respective groups. Suppression of the apical growth by vapour contact was ascribed to the direct deposition of essential oils on fungal mycelia, together with an indirect effect via the agar medium absorbed.

Inhibitory effects of some spice essential oils on Aspergillus ochraceus NRRL 3174 growth and ochratoxin A production.

Inhibitory effects of essential oils of oregano (Origanum vulgare), mint (Menta arvensis), basil (Ocimum basilicum), sage (Salvia officinalis) and coriander (Coriandrum sativum), on the mycelial growth and ochratoxin A production by Aspergillus ochraceus NRRL 3174 were studied. Cultures were incubated on yeast extract-sucrose (YES) broth, at concentrations of 0, 500, 750 and 1000 p.p.m. of essential oils during 7, 14 and 21 d at 25 degrees C. At 1000 p.p.m., oregano and mint completely inhibited the fungal growth and ochratoxin A production up to 21 d, while basil was only effective up to 7 d. At 750 p.p.m., oregano was completely effective up to 14 d, whereas mint allowed fungal growth but no ocratoxin A production up to 14 d. At 500 p.p.m., no evident inhibition could be in observed with any of the essential oils under analysis. Sage and coriander showed no important effect at any of the concentrations studied. These inhibitory effects are interesting in connection with the prevention of mycotoxin contamination in many foods and they could be used instead of synthetic antifungal products.

In vitro susceptibility of opportunistic Fusarium spp. to essential oils.

The inhibitory effects of essential oils extracted from 10 Indian plants were evaluated against five fungi. The plants used for extraction of essential oils were six species of the genus Eucalyptus and Ocimum basilicum, Prosopis cineraria and Derris indica. The fungi used in the experiments were Fusarium solani, F. oxysporum, F. pallidoroseum, F. acuminatum and F. chlamydosporum. The susceptibility of the Fusarium species was tested by the paper disc method and the serial dilution technique. The results were compared with the inhibitory effects of miconazole on the fungi. The essential oils extracted from the Eucalyptus species markedly inhibited fungal growth. Prosopis cineraria did not show inhibiting properties. Among the fungi, F. oxysporum proved to be the most resistant species.

Antibacterial activity of selected fatty acids and essential oils against six meat spoilage organisms

The antibacterial activity of selected fatty acids and essential oils was examined against two gram-negative ( Pseudomonas fluorescens and Serratia liquefaciens), and four gram-positive ( Brochothrix thermosphacta, Carnobacterium piscicola, Lactobacillus curvatus, and Lactobacillus sake) bacteria involved in meat spoilage. Various amounts of each preservative were added to brain heart infusion or MRS (deMan, Rogosa and Sharpe) agars, and the minimum inhibitory concentration was determined for each organism. Essential oils were analysed by gas–liquid chromatography to determine the concentration of selected components commonly found in spices. B. thermosphacta, P. fluorescens and S. liquefaciens were not affected by fatty acids, and generally overcame the inhibitory effect of essential oils after 24 h of exposure. Among the fatty acids, lauric and palmitoleic acids exhibited the greatest inhibitory effect with minimum inhibitory concentrations of 250 to 500 μg/ml, while myristic, palmitic, stearic and oleic acids were completely ineffective. For essential oils, clove, cinnamon, pimento, and rosemary were found to be the most active. The 1/100 dilution of those oils inhibited at least five of the six tested organisms. A relationship was found between the inhibitory effect of essential oils and the presence of eugenol and cinnamaldehyde.

Analysis of Volatile Components in Essential Oil of UplandWasabiand Their Inhibitory Effects on Platelet Aggregation

Inhibition of platelet aggregation was found in the essential oils extracted from the various parts of upland wasabi (Wasabia japonica forma terrestris Hisauti). The antiplatelet activity increased in the order of leaves, rhizomes, petioles, and roots. To examine the inhibitory principles in upland wasabi oil, components in each part of the essential oil were identified and measured. Most of the volatile components in upland wasabi oils were ω-alkenyl isothiocyanates and ω-methylthioalkyl isothiocyanates, allyl isothiocyanate being the main component in every oil. Essential oils from roots and petioles contained rather large amounts of ω-methylthioalkyl isothiocyanates. Although every authentic isothiocyanate inhibited platelet aggregation, ω-methylthioalkyl isothiocyanates were more inhibitory, which explained the stronger inhibitory effects of essential oils from roots and petioles on platelet aggregation.

Effect of Essential Oils on Aeromonas hydrophila in a Culture Medium and in Cooked Pork

The inhibitory effects of essential oils of coriander, clove, nutmeg, and pepper towards Aeromonas hydrophila were studied in tryptic soy agar. Essential oils of clove, coriander, and nutmeg at concentrations of 500, 1,250, and 10,000 μg/ml, respectively, were effective in inhibiting the growth of A. hydrophila on tryptic soy agar. Pepper was the least active oil of which 15,000 μg/ml appeared to inhibit only a diluted culture of A. hydrophila. Behavior of A. hydrophila was also evaluated in samples of noncured cooked pork treated either with coriander or clove oil. Meat samples were packaged either under vacuum or air and stored at 2 and 10°C. Both essential oils caused a marked reduction of A. hydrophila number. In the meat samples treated with clove oil and stored at 10°C, the lethal effect was significantly enhanced by the vacuum packaging. These data suggest that essential oils of coriander and clove could be used to control the hazard of A. hydrophila in noncured cooked meat at low and increased temperatures, especially in combination with vacuum packaging.

Antimicrobial Action of Citrus Oils

SUMMARY—The inhibitory effect of essential oils of orange and lemon oil and the antibiotics tylosin and nisin was tested on bacteria and fungi in nutrient media. Though the degree of inhibition varied with the culture, orange oil was a more effective antimicrobial agent than lemon oil. All other conditions being identical, 2, 000 ppm of orange oil had an effect similar to 10 ppm of tylosin, on all the gram‐positive cultures tried, including the spores of Bacillus subtilis. Moreover, orange oil was the only additive that showed inhibition of growth of the gram‐negative cultures, excepting Serratia marcescens. Yeasts, in general, were more sensitive than bacteria to orange oil, the effective dose being 500 ppm, at a cell concentration of 1 million/ml. This was a definite advantage over the antibiotics, which had no action on fungi. Though not so sensitive as the yeasts, the molds were also suppressed by orange oil at 2, 000 ppm. The possibility of using orange oil as a preservative in foods is indicated.